Devices and methods for injectable vascular sclerofoams using a carrier matrix and uses thereof

ABSTRACT

The invention relates in particular to an injectable sclerosant drug foam comprising: (i) a matrix; (ii) at least one fluid; (iii) at least one sclerosant drug; (iv) a medical gas or medical gas mixture acceptable for intravenous use, (v) wherein said matrix has physical properties, which are comparable to denatured blood, wherein the denatured blood is obtainable from a fresh human venous whole blood sample of 1 ml volume, which is heated in a cylindrical polyethylene container with 3 mm inner diameter and 3.4 mm outer diameter for about 0.5 min. to about 10 min. at a temperature of about between 70° C. and 100° C. and/or (vii) said level of denaturation is defined by the change of red-colored hemoglobin to brown as an indicator, wherein Fe 2+  is reduced to Fe 3+  in the hemoglobin complex to a degree of at least 80%, preferably 90% and even more preferably 95%.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a national phase filing of International PatentApplication No. PCT/EP2015/065142, filed Jul. 2, 2015, which claimspriority to European Application No. 14175609.8 filed Jul. 3, 2014, bothof which are herein incorporated by reference in their entireties.

FIELD OF THE INVENTION

The present invention relates to the field of medicine and therapeutics,particularly vein therapeutics, more particularly to the field ofsclerotherapy. Furthermore the invention relates to sclerosant drugs,particularly sclerosant drug foams and methods for the production ofsclerosant drug foams and uses thereof.

BACKGROUND OF THE INVENTION

Blood vessels in humans and animals are grouped as arterial and venous,determined by whether the blood in it is flowing away from (arterial) ortoward (venous) the heart. Veins collect blood from organs, muscle,connective tissue and skin. Venous blood has a low content of oxygen andnutrients, but enriched in carbon dioxide and final metabolism products.

Caused by acquired functional weakness due to lack of activity or bycongenital defects, a large number of people show venous congestion inthe legs. Congestion means a presence of blood above the physiologicallevel. If no change in habits occurs, congestion turns intoinsufficiency within few years. Insufficiency means that vein valvesbecome incompetent, resulting in a reversed blood flow. In a viciouscircle insufficiency further increases venous blood congestion, and thedisease increases with time. Varicose veins develop from insufficiency,they are superficial veins which have been stressed by an overload ofblood for years and therefore show large diameters and a tortuouscourse. Incompetent leg veins are found in 21-25% of people aged 35 orabove, and spider veins even in 50% (Uldis Maurins, Barbara H. Hoffmann,Christian Lösch, Karl-Heinz Jöckel, Eberhard Rabe, Felicitas Pannier:Distribution and prevalence of reflux in the superficial and deep venoussystem in the general population—results from the Bonn Vein Study,Germany. Journal of Vascular Surgery, Vol 48, Issue 3, September 2008,680-687).

Beside the cosmetic issues, insufficient and varicose veins lead tomajor complications, due to the congestion and the poor circulationthrough the affected limb. The complications comprise pain, heaviness,inability to walk or stand for long hours, skin inflammation, skindamage predisposing skin loss or skin ulcers especially near the ankle,usually referred to as venous ulcers, severe bleeding from minor trauma,blood clotting within affected veins (thrombophlebitis, thrombosis,embolic events). Some vascular malformations likeKlippel-Trénaunay-Weber of syndrome also go along with varicose veins.

For dilated veins, surgical removal of the target structure, e.g.varicose veins, has been a widely used therapy for decades. However,like all surgical treatments this may be accompanied by several,partially serious adverse effects, i.e. damaging of adjacent arteries,nerves or lymphatic vessels, generation of wounds and cicatrices, woundinfections, or intolerance of the patient for narcotic drugs.Furthermore, the tissue damage going along with every surgery, inparticular in junction regions like the groin or the popliteal areaseems to induce the growth of new, but diseased veins.

As an alternative to surgical removal, different ways of endovenousclosure methods have been developed, allowing minimal-invasivetreatments with a very low complication rate.

The term endovenous means, therapy is performed by catheter accessthrough the venous system, and within the diseased vein. Catheters aresmall-lumen tubes, inserted via a single puncture site. The aim of thesemethods is the permanent closure of the treated vein or vein segment.The effect may be obtained by thermal treatment (e.g. by laser,radiofrequency, steam), or by injection of chemical agents (fluids,foams, adhesives). Due to the use of catheters and probes, thermaltreatment and gluing is restricted to relatively linear vessels whilechemical agents may also reach curved and tortuous segments and branchedor reticular veins.

The effect of all the named endovascular methods applied to peripheralveins is to permanently denature functional proteins in the innermosttissue layer, the so-called endothelial cell layer. Said denaturingprocess triggers the aggregation of blood cells, in particularthrombocytes, at the vein wall. It is a kind of artificial thrombosiswhich occludes the vein. In contrary to incidental thrombosis which maybe hoped to resolve, in the therapeutic approach the aim is tocompletely denaturize all the endothelium in the segment to treat. Onlyparts of the vessel wall sufficiently reached by the thermal orsclerotic effect can be expected to close permanently, while undamagedendothelium will revitalize and lead to recurrent pathologic blood flow.All endovenous procedures are associated with a local vein spasm, due toeffects passing the endothelium layer and reaching the muscular layer.Spasm means a contraction of muscular cells, leading to an immediatereduction of the vein diameter. The vein spasm trigger by endovenoustechniques is in general not lasting longer than minutes above theactivity of the trigger. However, it would be desirable to maintain thespasm or the by spasm reduced vein size as long as it takes the bloodwithin the treated vein to clot, organize and fix the vein size.Occlusion and decrease in vessel diameter are the two most importantaims of this kind of therapy. A real initial shrinking could only beobtained by an effect reaching deep into the muscular layer with apermanent shortening of fibers. On the other hand, with increasingeffects on the muscular layer the danger of vein perforation increases,and so does pain during and after treatment as there are onlymicrometers distance to the highly innervated outer wall layer calledadventitia. All so far existing sclerosants or thermo-occlusivetechniques do not solve these problems and therefore are of limitedvalue. The use of adhesives could be a future solution, but techniquesare still insufficient and effective biocompatible and totallybiodegradable are not yet available for intravascular use.

Simple sclerotherapy is known for more than 60 years. Today's commonliquid sclerosant drugs are e.g. alcohols with detergent properties likepolidocanol or sodium tetradecyl sulphate. In the eldest modality, theliquid sclerosant drug is injected via metallic cannulas directly intothe vessels. Due to its high flowability the liquid sclerosant drugflows with the blood stream and quickly mixes with blood, soon reachingineffective dilutions. Blood protein bindings additionally limit theeffect of fluid sclerosant agents.

In order to circumvent some drawbacks of the liquid sclerosant drugs, ithas been established to produce a sclerosant foam by mixing the liquidsclerosant drug with a gas. The resulting sclerosant drug foam isinjected into the target structure, e.g. the varicose vein. For foamingthe sclerosant drug (e.g. sodium tetradecyl sulfate or polidocanol) ismixed with sterile air or a physiological gas (carbon dioxide, oxygen)in a syringe or by using mechanical pumps.

In the literature, the terms “foam sclerotherapy”, “sclerofoam”,“microfoam” and “sclerosant drug foam” are used. Sclerofoam can beproduced by mixing liquid sclerosant with a medical gas like O₂ or CO₂,or room air, using the TESSARI method by 10-20 times to- and frominjection from one syringe to another via stopcock or Luer-connector, byshaking a syringe, simultaneous aspiration of fluid and gas, ormechanically by pumps, positive or negative pressure devices, perforatedoutlets or valves, or by propellers or rotating brushes (GEROULAKOS G.:Foam sclerotherapy for the management of varicose veins: a criticalreappraisal, Phlebolymphology Vol 13, No. 4 (2006) p 181-220).

If injected properly, foam will replace blood totally for a certaintime, varying from seconds to a few minutes. In this time, the contactto the vein wall is more intense than in case of a liquid bolus justpassing by. The chemical reaction of the sclerosant on the endothelium(innermost wall layer) will expand to the media layer and triggermuscular spasms, which may be more intense than in the case of fluidsclerosants of the same chemical concentration.

Foaming increases the surface area of the drug. Due its higher stiffnessand viscosity, the sclerosant drug foam is more efficacious in causingsclerosis than the liquid sclerosant drug (Thickening of the vessel walland sealing off the blood flow; Yamaki T, Nozaki M, Iwasaka S:Comparative study of duplex-guided foam sclerotherapy and duplex-guidedliquid sclerotherapy for the treatment of superficial venousinsufficiency, 2004, Dermatol Surg 30 (5): 718-22; Evaluation of theEfficacy of Polidocanol in the Form of Foam Compared With Liquid Form inSclerotherapy of the Greater Saphenous Vein: Initial Results; ClaudineHamel-Desnos, Philippe Desnos, Jan-Christoph Wollmann, Pierre Ouvry,Serge Mako, François-Andre Allaer, Dermatol Surg 29 (12): 1170-1175(2003); WO 95/00120 J. Cabrera et al. 1995).

Besides the viscosity, an important property of sclerofoam is itsvisibility in ultrasound scans due to the contents of gas which reflectsthe sound energy (FIG. 1). Therefore, foam injections can be ultrasoundmonitored and the dosage can be adapted to the individual requirements,which is not feasible with fluid sclerosants as their signal does notdiffer from fluid blood.

However, the gas may accumulate and lead to acoustic shadows, hidingrelevant anatomic structures. It is rarely possible to tell if all thelumen is completely filled with foam, or if there is just a layer offoam floating on blood (FIG. 1).

Although some ultrasound contrast media have been developed, e.g. US20020031476 A1 disclosing a stabilized gas emulsion containingphospholipids for ultrasound contrast enhancement, or U.S. Pat. No.4,466,442 A disclosing carrier liquid solutions for the production ofgas microbubbles as contrast medium for ultrasonic diagnostics usingtensides, such media have not been used to optimize sclerotherapy.

In clinical practice the majority of sclerotherapies are not complete inthe sense of total circumferential endothelium denaturation. Forexample, in case of slow injection, and as well in case of complex andtortuous varicose formations which limit the injection velocity, foamwill float on blood instead of replacing it. Only partial denaturationof the endothelium will be achieved. Trials have shown that even byaxially turning the patient for 180 degrees the foam will notsufficiently reach the opposite vein walls.

There are some more drawbacks of common sclerofoam: If an injection isperformed too fast, foam will also spread to healthy veins and may leadto unintended closures or thrombosis. When a vein shrinks after foaminjection by foam-induced spasm to a percentage of its originaldiameter, significant amounts of foam will migrate to diseased orhealthy neighbouring vessels with the same consequence. Common foams aremechanically too weak to resist and stay in place.

In the initial experience it was most welcome that the foam collapseswithin a short time, coming from the idea of rapid elimination. However,due to rapid foam collapse all the chemicals are transferred to thecirculation within minutes which may lead to side effects likebronchospasms or vision disorders. The lack of stability seems to be themost important drawback of common sclerosant foams.

The process of sclerotherapy in detail is this: If sclerofoam isinjected into a diseased vein, it replaces the blood, touches the veinwall and triggers a vein spasm. This can be felt during foam injectionas an increase of resistance, which is regarded as a sign to stop theinjection. As native side branches now have low flow resistance comparedto the spastic target vein, a further injection would go there which isnormally not intended. If a foam injection is stopped in time,undisturbed collateral flow will dilute small amounts of overdosage andprevent side effects.

The musculature of spastic veins will relax within 5-60 minutes afterfoam injection, and remainders of common foam will at the latest then bewashed off. When the vein spasm vanishes, blood will return to thetarget vessel. Although by external compression (stockings, bandages)the amount of blood returning to the treated vein can be reduced to someextent, it cannot be avoided effectively or even completely.

The vein will close within several hours to few days after foaminjection. However, vein closure may not only occur due to endotheliumdenaturation, but also if just parts of the endothelium have beendenaturized, as occlusive thrombus may form there and reduce or stop theblood flow. Then further parts of vein segment will close due tothrombosis, which will appear as a success. However, all thromboticocclusion in regions without complete endothelium denaturation isreversible as endothelium is still vital. Therefore, any closure provedby ultrasound examination within days or weeks post treatment does in noway prove endothelium destruction or a success of foam treatment. Ifclosure of this kind occurs, it will not be complete, not stable, orshow early relapse. In fact, many cases of “relapse” within the firstyears represent failed primary endothelium destruction, caused byinsufficient foam distribution.

In the case of incomplete endothelium destruction, thrombotic andrecanalisation phases will compete and clinically appear as painfulphlebitis. This is often clinically more intense than generalinflammatory reactions after endothelium denaturation.

An optimized foam should be able to completely replace blood in adiseased vein due to much higher viscosity, and thus solve the problemof incomplete foam treatments.

At the point of primary vein closure, there is no more perfusion in thisvessel, and the pathological backward flow is eliminated. This is thesame hemodynamic effect like achieved by surgery (“elimination ofreflux”), and it is the main endpoint of treatment quality.

In contrary to surgery, the vein is still in place. For optimal results,it should now be neither visible nor palpable. The patient should notfeel its existence when moving or at rest. However, this aim is notreached for larger veins by today's sclerotherapies. The reason is thatthese techniques only trigger a complex process of shrinking andorganization which will take weeks to many months, depending on the sizeof the vein.

Frequently, the vein regains the same diameter it had before treatment.The total amount of clotted blood contained in the vein at the time oftotal occlusion will determine the duration and symptoms of theorganization process. Clotted blood within the vessel will have to beremoved by metabolism, performing a change from a large thrombotic veinto a small string of connective tissue. As a fact, the incidence ofunwanted side effects like painful inflammations, brownishdiscolorations, long-lasting indurations and still visible varicoseveins rises with the vein diameter and may occur in up to 80% of thetreated cases.

It is assumed that the effect of sclerofoam treatments depends on itsphysical stability. The stability of foam sclerosants is appreciated bythe so called volume half life, telling the time until 50% of the foamis collapsed. Common volume half lives of polidocanol microfoams made insilicone-free plastic syringes are 60-180 s. Using glass syringes andforced foaming procedures by to- and from injections from one syringe toanother, volume half times of 210 s can be obtained and much betterresults are observed after applying this kind of foam.

So, one major aim for an optimized foam sclerosant is, to obtain aprolonged volume half life. If achievable, also the effect on theendothelium would be stronger. Using the same concentration ofsclerosant, the denaturing effect would grow with the time ofinteraction to the vessel wall. The dosage of the chemical agent couldpotentially be reduced.

As sclerofoams of prior kind disintegrate quickly, the rate of unwantedside effects is high: Thrombosis (occlusion of deep veins) caused bymigrated foam appears in a rate of up to 4%. Unwanted closure of healthyepifascial veins is estimated at up to 20%, while the clinical sequelaeare yet unknown.

Most of conventional foam therapies require several sessions for theaimed success. Sometimes, treatment plans consist of 5-10 visits. Thisis time consuming for patient and physician. Also the wearing time ofbandages or stockings is prolonged.

Summarizing, when treating diseased veins with common sclerotherapytechniques, many attempts are incomplete, induce relevant side effectsor frequently show relapse. The diseased vein will not be permanentlyclosed at the end of the procedure. There may remain a space consumingand symptomatic structure for weeks to months. It would be advantageousto have means for instantaneous and permanent closure of diseased veins.

There have been several attempts to improve foam sclerotherapy. WO2006/037735 A1 discloses a device for producing a medical foam by usingsealed containers for sterile sclerosant and sterile gas, whichcontributes to hygienic aspects and simplification of the procedure asgas and sclerosant do not have to be aspirated from larger containers.However the insufficient physical features of the foam remain unchanged.

Improved therapeutic sclerofoams generated by pressurized gas aredisclaimed in U.S. Pat. No. 8,091,801 B2. However, also these foamshardly reach volume half times above a few minutes.

The generation of therapeutic microfoam with gases like carbon dioxideor xenon has been proposed to reduce side effects induced by largeamounts of slow resorbable gases like nitrogen, e.g. disclaimed in U.S.Pat. No. 7,357,336 B2. However, such side effects are rarely seen whenapplying foam volumes less than 10 cc per session. The technical foamproperties are not significantly changed, in particular the half-liveremains insufficiently short.

To overcome all the drawbacks of sclerosant drugs and sclerosant drugfoams of prior art the ideal sclerosant substance has to fulfill avariety of features: It should have a significantly increasedconsistency or stiffness to fill the target vein completely andprecisely. The viscosity should be adjustable for different approaches,e.g. less viscous for injection in small and long cavities, or highlyviscous for short or large cavities. It should allow injection viacatheters. It should induce long lasting spasms of the targetstructures. After injection into the target structure foam should remainwithin said structure until its completed occlusion. Foam within thetarget vein should dissolve slowly to reduce the inflow of chemicalagents to the circulation. For this purpose, the foam should have avolume half-life of hours to days. It should be clearly visible inultrasound scans but, nevertheless, it should not produce relevantacoustic shadows and always show all relevant tissue and vesselstructures. It furthermore has to be safe for application in humans, inparticular rates for unwanted side effects like thrombosis or embolismshould be significantly lower than in former foam techniques andproducts. It finally should not contain other chemicals than thesclerosant, and should be 100% biocompatible and biodegradable. Thus theproblem is to provide a sclerosant drug foam with the desiredproperties.

BRIEF DESCRIPTION OF THE INVENTION

The present invention relates to a sclerosant drug foam comprising amatrix. Preferably said matrix comprises denatured blood, preferablyprepared from an autologous blood sample, disperged with at least onefluid and at least one sclerosant drug, and foamed with a gas useablefor intravenous application.

The invention relates in particular to an injectable sclerosant drugfoam comprising:

-   -   (i) a matrix;    -   (ii) at least one fluid;    -   (iii) at least one sclerosant drug;    -   (iv) a medical gas or medical gas mixture acceptable for        intravenous use,    -   (v) wherein said matrix has physical properties, which are        comparable to denatured blood, wherein the denatured blood is        obtainable from a fresh human venous whole blood sample of 1 ml        volume, which is heated in a cylindrical polyethylene container        with 3 mm inner diameter and 3.4 mm outer diameter for about 0.5        min. to about 10 min. at a temperature of about between 70° C.        and 100° C. and/or    -   (vii) said level of denaturation is defined by the change of        red-colored hemoglobin to brown as an indicator, wherein Fe²⁺ is        reduced to Fe³⁺ in the hemoglobin complex to a degree of at        least 80%, preferably 90% and even more preferably 95%.

-   In a particular embodiment the invention relates in particular to an    injectable sclerosant drug foam comprising:    -   (i) denatured blood;    -   (ii) at least one fluid;    -   (iii) at least one sclerosant drug;    -   (iv) a medical gas or medical gas mixture acceptable for        intravenous use,    -   (v) wherein the denatured blood is characterized by a certain        level of denaturation,    -   (vi) wherein said level of denaturation is defined by the color        of the denatured blood and said color of denatured blood is        comparable to or identical to blood being denatured as follows:        -   a fresh human venous whole blood sample of 1 ml volume is            heated in a cylindrical polyethylene container with 3 mm            inner diameter and 3.4 mm outer diameter for about 0.5 min.            to about 10 min. at a temperature of about between 70° C.            and 100° C. and/or    -   (vii) said level of denaturation is defined by the change of        red-colored hemoglobin to brown as an indicator, wherein Fe²⁺ is        reduced to Fe³⁺ in the hemoglobin complex to a degree of at        least 80%, preferably 90% and even more preferably 95%.

As there are multiple ways to denature human blood, the desired effectis defined by one particular embodiment of the invention, obtainingdenaturation of a whole blood sample of 1 ml volume in a cylindricalpolyethylene container with 3 mm inner diameter and 3.4 mm outerdiameter, heated by circumferential contact to a heating element for0.5-10 min. at temperatures between 75 and 100° C., using the change ofthe red color of hemoglobin to brown during heat exposure as anindicator for the appropriate degree of denaturation. The denaturationrequired for this specific purpose may be obtained by heat conduction,heat or energy radiation or by mixing with heated fluids or gases.

In a preferred embodiment the denatured blood corresponds to a wholeblood sample of 1 ml volume in a cylindrical polyethylene container with3 mm inner diameter and 3.4 mm outer diameter, heated by circumferentialcontact to a heating element for 3 min. at 81° C.

Dispersion is obtained by mixing denatured blood with at least one fluidand at least one sclerosant medium, using mechanical forces likeacceleration and slow down of fluid beams to obtain small particlesdisperged in fluid.

The sclerosant foam is obtained by mixing the dispersion including atleast one sclerosant agent with a medical gas like O₂ or CO₂ orcompositions thereof.

The invention further relates to a method for the production of asclerosant drug foam based on a matrix comprising the following steps:

-   -   (a) generation of a stabile matrix    -   (b) dispersing the matrix within a pharmaceutically acceptable        liquid by applying forces to obtain a particle size of 5-300 μm,        preferably <120 μm, even more preferably <50 μm wherein in one        embodiment the pharmaceutically acceptable liquid is or        comprises said at least one sclerosant drug;    -   (c) mixing the dispersion with at least one sclerosant drug if        not performed in step (b) (d) optionally filtering the        suspension or emulsion to exclude particles larger than 50-120        μm;    -   (e) foaming the dispersion with a gas which is acceptable for        intravenous use;

The invention further relates to a method for the production of asclerosant drug foam based on a human blood matrix preferably made fromautologous blood comprising the following steps:

-   -   (a) denaturation of a blood sample    -   (b) dispersing denatured blood within a pharmaceutically        acceptable liquid by applying forces to obtain a particle size        of 5-300 μm, preferably <120 μm, even more preferably <50 μm        wherein in one embodiment the pharmaceutically acceptable liquid        is or comprises said at least one sclerosant drug;    -   (c) mixing the dispersion with at least one sclerosant drug if        not performed in step (b)    -   (d) optionally filtering the suspension or emulsion to exclude        particles larger than 50-120 μm;    -   (e) foaming the dispersion with a gas which is acceptable for        intravenous use;

The invention also relates to a device (FIG. 5) for the production of asclerosant drug foam comprising:

-   -   (a) a catheter for blood sampling and foam distribution (1),    -   (b) a first container (4) for blood collection and denaturation,    -   (c) an external element for denaturation by heat, radiation or        chemicals (6) to be physically or thermically connected to the        first container,    -   (d) a second container (10) for at least one fluid and/or at        least one sclerosant agent,    -   (e) a unit (7 a) to apply mechanical force to the contents of        the first and/or second container for mixing/dispersing,    -   (f) a chopping element (7 b),    -   (g) a filter element (13),    -   (h) a third container to hold the dispersion (14), a fourth        container containing a medical gas (18),    -   (j) a unit (16) to apply mechanical force to the contents of the        third and/or fourth container for foaming,    -   (j) two-way switches, one-way valves, single stop cocks or        combinations thereof (2, 3, 9, 15, 17),    -   (k) auxiliary access to the device, e.g. to apply negative or        positive pressure, or to supply fluids or gases (4 a, 8, 11 a,        11 b, 19)    -   (l) connection elements connecting all modular parts.

Here, an amount of blood is taken from the target vein through thecatheter (1) and guided to the first container (4) where the blood isdenatured by help of the denaturation unit (6). The denatured blood ismixed with a fluid and/or a sclerosant agent from a second container(10) to form a dispersion by application of mechanical forces (7). Ifthe mixing procedure alone would leave particles above 120 μm, achopping unit (7 b) is added and the dispersion passed once or severaltimes. To ensure no particles above 120 μm are present in thedispersion, it may be filtered (13) and guided to a third container(14). Then a connection to a fourth container (18) providing a medicalgas is established and a foam produced by mixing the gas with thedispersion by applying mechanical force (16). The foam is finallyprovided in one of the containers (14, 18) and transferred to thediseased vein via catheter (1).

The invention further relates to a kit for the production of thesclerosant drug foam comprising:

-   -   (i) a device for sterile denaturing of autologous blood    -   (ii) optionally at least one liquid    -   (iii) optionally at least one sclerosant agent, if not included        in (ii)    -   (iv) optionally a medical gas like CO₂ and/or O₂ or a mixture        thereof    -   (v) optionally one or several catheters for venous access and        foam deployment

The invention further relates to a method of treating venousinsufficiency using a sclerosant drug foam based on a matrix ofdenatured blood, comprising the steps of:

-   -   (i) accessing the diseased vein    -   (ii) preparing the sclerosant drug foam on a basis of denatured        blood    -   (iii) deploying the sclerosant drug foam along the diseased vein

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a sclerosant drug foam comprising amatrix. Preferably said matrix comprises denatured blood or has physicalproperties analogous to denatured blood.

The invention relates in particular to an injectable sclerosant drugfoam comprising:

-   -   (i) a matrix;    -   (ii) at least one fluid;    -   (iii) at least one sclerosant drug;    -   (iv) a medical gas or medical gas mixture acceptable for        intravenous use,    -   (v) wherein said matrix has physical properties, which are        comparable to denatured blood, obtainable from a fresh human        venous whole blood sample of 1 ml volume, which is heated in a        cylindrical polyethylene container with 3 mm inner diameter and        3.4 mm outer diameter for about 0.5 min. to about 10 min. at a        temperature of about between 70° C. and 100° C. and/or    -   (vii) said level of denaturation is defined by the change of        red-colored hemoglobin to brown as an indicator, wherein Fe²⁺ is        reduced to Fe³⁺ in the hemoglobin complex to a degree of at        least 80%, preferably 90% and even more preferably 95%.

The inventor found that a stabilizing matrix needs physical properties,which are a high viscosity. The viscosity of the matrix can be measuredusing a ball test, wherein the foam is prepared in a 10 ml syringe, thesyringe placed in a 60° angle from horizontal inclined position. A smallround ball of 13 mm diameter and 1.3 g in weight is placed on top of thefoam and velocity of the ball moving through the foam is measured. Usingthis setting, the velocity of the ball is 1.7-2.3 cm/s in commonmicrofoams.

In a preferred embodiment of the invention the foam slows the ball to avelocity of less than 1 cm/s, preferably less than 0.7 cm/s, morepreferably less than 0.5 cm/s, most preferably less than 0.25 cm/s.

The term “matrix” defines a structure which serves as a physicalcarrier. This does not exclude few chemical bindings, but the maineffect is physical. To avoid or reduce chemical bindings of thesclerosant agents, these are preferably added after appropriategeneration of the matrix.

It is preferable that the foam comprising the matrix has a longerhalf-life in vitro than common sclerosant foams, while still beingbiologically degradable. Preferably the foam comprising the matrix has ahalf-life of at least 30 minutes or longer, more preferably at least onehour or longer, even more preferably at least two hours, more preferablyat least four hours, most preferably at least six hours.

In a preferred embodiment of the invention the foam comprising thematrix is stable inside a vein for at least 4 hours, meaning after 4hours the foam is still visible in ultrasound imaging.

In a preferred embodiment of the invention the matrix is a composition,which has physical properties comparable a blood sample of 1 ml kept ina cylindrical polyethylene container with 3 mm inner diameter and 3.4 mmouter diameter is denatured by conducted heat for 0.2 to 10 minutes atbetween 50 to 100° C., more preferably 0.4 to 7.5 minutes at 60 to 100°C. and most preferably for 0.5-7 minutes at 75-100° C., referring to theheating temperature at the outer margin of the blood sample container.

In a preferred embodiment the matrix has physical properties comparableto denatured blood, which corresponds to a whole blood sample of 1 mlvolume in a cylindrical polyethylene container with 3 mm inner diameterand 3.4 mm outer diameter, heated by circumferential contact to aheating element for 3 min. at 81° C.

In preferred embodiments the matrix is a biocompatible composition. Morepreferably the matrix is a biocompatible, pharmaceutically acceptablecomposition.

Suitable matrix compositions are known to the person skilled in the art.In preferred embodiments the matrix comprises various biodegradablepolymers-PCL, PLA and PLGA alone or in combination. Alternatively crosslinked hyaluronic acid and/or a mixture of denatured human proteins,e.g. denatured human serum albumin or synthetic similar proteins mightbe used.

The inventor unexpectedly found that a dispersion of denatured humanblood can be used as a carrier for foaming liquid sclerosant chemicalswith all the desired features and properties. The inventor found thatsclerosant drug foams comprising denatured blood of the patient's ownblood show stunningly improved properties. In particular, the sclerosantdrug foam according to the present invention has a half live of 2 h to14 days which increases the time of contact between the sclerosant drugand the target structures (FIG. 3). Thereby, efficiency of thesclerotherapy is unexpectedly increased. The foam according to thepresent invention shows a tremendously higher stiffness than sclerosantfoams of prior art (FIG. 3). Stiffness and density can be adjusted bythe ratio of blood, liquid, sclerosant agent and gas. In contrary to thedisadvantageous sound shadows of common foams (FIG. 1) the ultrasoundappearance of the blood matrix based foam varies from neglectableacoustic shadow to no shadow at all (FIG. 2). The application is moreprecise (FIG. 4), restricting the effect to the diseased target vein andpreserve healthy veins. The spasm period is much longer, as spasmdepends on the presence of the sclerosant agent, which is longer held inplace by the blood-based matrix. The distribution of chemicals to thecirculation is much slower and therefore side effects even rarer than inconventional sclerosant foams. The target vein occlusion occurs muchfaster and with a smaller final lumen, supporting a short and symptomfree healing period.

The patient's own blood seems to be the most natural and the safestsource of particles to produce sclerosant foam with improved properties.As denaturation leaves the primary structure of blood proteinsunchanged, adverse reactions due to the matrix are not to be expected.

Although blood samples could be processed in a laboratory, the aim ofthe invention is to provide a closed system where a sterile foam isproduced in a system attached to the catheter and injected without anycontact to the environment. Technology even allows miniaturization toinstall the system totally inside of a catheter, or systems workingwithin a catheter extension.

The invention further relates to a particular injectable sclerosant drugfoam comprising:

-   -   (i) denatured blood;    -   (ii) at least one fluid;    -   (iii) at least one sclerosant drug;    -   (iv) a medical gas or medical gas mixture acceptable for        intravenous use,    -   (v) wherein the denatured blood is characterized by a certain        level of denaturation,    -   (vi) wherein said level of denaturation is defined by the color        of the denatured blood and said color of denatured blood is        comparable to or identical to blood being denatured as follows:        -   A fresh human venous whole blood sample of 1 ml volume is            heated in a cylindrical polyethylene container with 3 mm            inner diameter and 3.4 mm outer diameter for about 0.5 min.            to about 10 min. at a temperature of about between 70° C.            and 100° C. and/or    -   (vii) said level of denaturation is defined by the change of        red-colored hemoglobin to brown as an indicator, wherein Fe²⁺ is        reduced to Fe³⁺ in the hemoglobin complex to a degree of at        least 80%, preferably 90% and even more preferably 95%.

For the purpose of the present invention the term blood refers to humanvenous whole blood. Preferably the blood is whole blood of the patient.

In the present invention the expression “denatured blood” is frequentlyused. For several purposes, it may be adequate to keep certain proteinsvital, like those for coagulation. On the other hand, calling theprocedure “partial denaturing” would not express that a majority of theproteins has to be denatured. The desired degree of denaturation in thesense of the invention is defined as preferably exceeding 90% of thecontained blood proteins and blood cell proteins.

Blood denaturation may be performed by heat, in particular conductedheat. Blood may also be denatured by radiation, such as microwave,radiofrequency, infrared or other kinds of electromagnetic radiation, orby chemical means including enzymes. Depending on the kind ofdenaturation, different arrays may be required for a device producingblood-based sclerofoam (FIG. 5 a-c), and all features shown in thosearrays may be combined.

The term “matrix” defines a structure which serves as a physicalcarrier. This does not exclude few chemical bindings, but the maineffect is physical. To avoid or reduce chemical bindings of thesclerosant agents, these are always added after appropriate denaturationof the blood sample.

In a preferred embodiment of the invention a blood sample of 1 ml keptin a cylindrical polyethylene container with 3 mm inner diameter and 3.4mm outer diameter is denatured by conducted heat for 0.2 to 10 minutesat between 50 to 100° C., more preferably 0.4 to 7.5 minutes at 60 to100° C. and most preferably for 0.5-7 minutes at 75-100° C., referringto the heating temperature at the outer margin of the blood samplecontainer.

The term denaturation means the process of irreversible changes in thenatural 3-dimensional structure of proteins. In heat denaturation notonly heating temperature and exposure time will determine the result,but the distribution of temperatures within the sample over time. Due togeometric factors any heating process will create different temperaturesin a sample at a given time, comparable to the boiling of an egg.Therefore, the required sample temperature can only be given with atolerance of 5-10% as it is rarely uniform throughout the sample.

Heat denaturation starts at about 50° C. with dissolving of the internalhydrogen bonds, proteins unfold and lose their biological function. Thiscorrelates with the inactivation of most of the vital enzymes.

In the range of 60-65° C. hemoglobin will change to methemoglobin byiron oxidation, predominantly responsible for a change in color from redto brown. At the same time, haemolysis and coagulation occur. Membranelipids will melt and cell structures disintegrate. Above 70° C. alsodisulfide bridges will dissolve, which form the intermolecularconnections. In consequence the shape of spherical proteins will changeto filiform. Blood serum will form a solid gel starting at 72° C. Above80° C. proteins will even lose their secondary structure. However, theprimary structure is maintained and there is no change in the chemicalcomposition.

The inventor observed two signs indicating the desired degree ofdenaturation of 2 ml human whole blood samples in glass test-tubes of1.8 cm diameter, heated in a water bath of 60-80° C. will change theircolor from red to brown within 4-18 minutes. It could be shown that thiscolor change correlates to the quality of the foam produced, accordingto its half-life. Therefore, the color change was adapted as a majorcriterion for producing a foam according to the invention. Using smallertubes, the required time to denaturation was much shorter (Tab. 1 a-b).

Temperatures of above 100° C. may further accelerate blood denaturation,and such procedures are feasible when increased pressure is tolerated bythe device.

In a preferred embodiment the denatured blood corresponds to a wholeblood sample of 1 ml volume in a cylindrical polyethylene container with3 mm inner diameter and 3.4 mm outer diameter, heated by circumferentialcontact to a heating element for 3 min. at 81° C.

The color of the blood changes with the degree of denaturing.Non-denatured, native, oxygenated blood exhibits a bright red color.Deoxygenated blood, e.g. from veins, has a darker shade of red.Denaturing or partially denaturing of the blood triggers a change of thecolor of the blood. Denatured blood in the context of the presentexhibits a dark brown color.

Table 3 a, b: These tables show the time required to obtain a colorchange from red to brown, depending on the size of the sample and thesurrounding temperature. For medical purpose, all the sample volume hasto be denatured. Therefore, the color was measured by a colorimeterwithin the center of the probe.

TABLE 3a color change from red to brown in a sample measuring r = 1.9 mmand length = 80 mm Temperature in ° C. 60 65 70 75 80 85 90 95 time — —6 4 3 2 1 0.5

TABLE 3b color change from red to brown in a sample measuring r = 7.0mm, length = 2.5 mm Temperature in ° C. 60 65 70 75 80 85 90 95 time — —12 10 8 6 4 2

As color impressions may depend on the investigator's eye it isimportant to define “red” and “brown”. Although there is a wide colorrange depending of the degree of oxygenation, nutrition factors andmaybe medication, “red” can be defined in several ways. One way is incomparison to standardized colors, like the German RAL color numbersystem. Another way is according to RGB values, which is often used incolorimetric measurements. In the context of the invention, “red” isdefined as being RAL 3003, or RGB 184-26-14, while RAL 3004 isindefinite, equivalent to RGB 109-29-20. RAL 3003 is “brown”, equivalentto RGB 141-26-33. Other “brown” colors observable in denaturized bloodsamples according to the invention are e.g. RAL 3005-3011, 8007-8017 and8023-8025. Other “red” colors of native or not sufficiently denaturizedblood samples are represented by e.g. RAL color numbers 3000-3003, 3013,3016, and 3027.

As a more precise alternative, “brown” in the sense of the invention canbe defined as a state where more than 80%, preferably more than 90% andeven more preferably more than 95% of the iron has turned from Fe²⁺ toFe³⁺. This classification is based on laboratory tests and is notsuitable for an immediate use in clinical application, but can be usedfor calibration. The amount of oxidized iron could be determined usingoximetry.

One further feature of a heat-treated blood sample suitable forproducing a carrier for sclerosant media is the firmness of thesubstance due to denaturation and coagulation. If blood denaturedaccording to the invention is spread from a syringe to a tissue, itappears as a stable body which does not visibly change its shape as faras no external forces are applied (FIG. 6). This feature also may beused to define appropriate denaturation.

The following explanations relate to both, the sclerosant drug foamcomprising a matrix and the particular embodiment comprising denaturedblood.

In most embodiments the at least one fluid is a pharmaceuticallyacceptable liquid, which is used to disperse the denatured blood.

In some embodiments of the invention the denatured blood is dispersedwith a pharmaceutically acceptable liquid, which are preferablydistilled water purified for injection purpose, or a sterile isotonicsodium chloride solution. In a preferred embodiment of the invention thepharmaceutically acceptable liquid also comprises the sclerosant drug indissolved or suspended form. In a more preferred embodiment thepharmaceutically acceptable liquid is the sclerosant drug.

A sclerosant drug in context of the method for production of asclerosant drug foam may be any substance which is suited forsclerotherapy, i.e. which changes the protein structures of veinendothelium in the sense of a permanent denaturation within a fewseconds of contact. In a preferred embodiment the sclerosant drugaccording to the invention is selected from the group consisting ofalcohols with detergent properties such as, polidocanol or sodiumtetradecyl sulphate. Different dilutions of the drugs are availablecommercially. For polidocanol solutions with concentrations ranging from0.25% to 4% in suited solvents (e.g. ethanol) are available (e.g.Aethoxysklerol, Kreussler Pharma, Germany). Thus, in a preferredembodiment the sclerosant drug is a solution of 0.1% to 10% polidocanolin a suited solvent, preferably 0.2% to 7%, even more preferably 0.25%to 4% polidocanol in a suited solvent. The most preferred concentrationis between 1% and 3%.

To produce sclerosant foams according to the invention, the dispersionof denatured blood is mixed with a medical gas or gas mixture acceptablefor intravenous use. Such gases are N₂, O₂ and CO₂, and even filtratedroom air is appropriate for foam preparation with recommended maximalinjection of 8 ml.

For use in the treatment of insufficient veins, for a 10 ml quantity ofinjectable sclerosant foam compositions of 1-4 ml denatured blood, 2-6ml of disperging fluid and 2-6 ml of medical gas is suggested, whilehigher quantities of denatured blood will produce higher viscositieswith potential advantages for use in short-distance targets and higherquantities of fluid and gas will produce foams of lesser viscositiessuitable to reach locations even at above 10 cm distance from thecatheter outlet.

It is clear to the person skilled in the art that a sclerosant drug foamfor use as a medicament has to be prepared immediately before use.

Methods of foaming are known by those skilled in the art. One way is tomix the dispersion containing the matrix and/or preferably denaturedblood, at least one liquid and at least one sclerosant drug with a gasor a gas mixture and obtain a foam when specific forces are reached. Anyof the known methods to prepare sclerosant foams will be applicable.Another way to prepare foam based on a matrix preferably of denaturedblood is to use gas or steam already during the step of generating thematrix by obtaining a primary foam, and then add a liquid sclerosantmedium and conclude with a final mixing and foaming.

The inventor found it desirable to fragmentize the matrix or thedenatured human blood or fractions thereof to particles below monocytesize (120 μm) in order to circumvent the danger of embolism or damagesin other organs. The procedural aim of particle size is 5-300 μm,preferably 5-120 μm, even more preferably 5-50 μm. The foam bubble sizeis 10-300 μm, preferably 20-200 μm, even more preferably 30-120 μm.

Particle size can be minimized by increasing the forces applied to thedispersion, or by including cutting means. Similarly, bubble size can beminimized by increasing the forces applied during foaming.

In another embodiment of the invention the particle size is reduced byuse of a chopping element. A preferred chopping element for use in thisinvention comprises: at least one cutting edge, preferably severalcutting edges located within a connecting tube structure, wherein thecutting edges are arranged to face the particle inflow and cover lessthan 10% of the tube cross-section area. Preferably, the flow ofparticle-containing fluid or dispersion is accelerated before hittingthe chopping element.

A “cutting edge” in context of the present invention is an edge, whichis suited to chop particulates of partially denatured blood whenapplying a force on the particulates with said edge. The two cuttingedges may be connected, i.e. they are formed by one cutting means. Thus,in one embodiment of the present invention the at least two cuttingedges are formed by one double edged cutting means. In a furtherembodiment each of the at least two cutting edges is formed by aseparate cutting means.

By “cutting means” in context of the present invention are meanscomprising at least one cutting edge. The material of cutting means maybe selected by those skilled in the art. The skilled person willunambiguously recognize that the material, however, has to provide acertain degree of rigidity to allow the cutting edge(s) to chopparticulates of partially denatured blood. In one embodiment the cuttingmeans consists of a material selected from the group consisting ofmetal, steel, plastic, glass, ceramic or the like. In one embodiment thecutting means is a double edged blade. In a further embodiment thecutting means is one double edged cutting wire.

Mechanical forces are required for the transport of blood, fluids,dispersion, gas and foam within the system, and in particular fordisperging, filtering and foaming. In a preferred embodiment, mechanicalforces are generated by external pressure. This may include positive andnegative pressure, or alternating pressures. Pressures can be obtainedby pneumatic or hydraulic elements, but also by electromechanicelements. Another means to execute forces is by rotational device likepropellers, which are usually electricity driven.

While the parts transferring energy to denatured blood, fluids or thedispersion (FIG. 5) are mandatory elements of the device, the source ofthe applied energy may be external, e.g. as rotational motor or pressuredevice, and the energy is transmitted via particular connectors.

A dispersion is a system in which particles are dispersed in acontinuous phase of a different composition or state, and the expressionis less precise than “suspension” and “emulsion”, which may both beinvolved when dealing with blood. In the present case a dispersion iscreated from denatured blood and at least one fluid like isotonicsaline. While blood denatured by conducted heat forms a kind of a solidbody, other modi of denaturation like chemicals or mixing with heatedfluids or gases will not form solid bodies. Therefore, the term“dispersion” was chosen to characterize a mixture of small solid orfluid particles within another fluid, with no visible precipitationduring the phase until it is transferred to a foam by mixing with gas.

To obtain a determined maximum particle size with the aim to minimizethe risk of microembolism, in a preferred embodiment the sclerosant drugfoam is filtered during production. In a preferred embodiment of theinvention this filtration step removes all particles exceeding a size ofgreater than 120 μm. This equals the size of the biggest natural bloodcells.

In a foam according to the invention, the denatured blood content is10-50% of the foam volume. As there are recommendations of a recentConsensus Conference concerning limiting the amount of common sclerosantfoam per session to 10 ml, a similar recommendation may be derived alsofor the sclerosant foam according to the invention. As about 44% ofwhole blood volume is cellular, and percentage of denatured blood in thefoam is 10-50%, the maximum amount of denatured blood cells is 2.2 ml.All blood cell remnants from the foam can be disintegrated by naturalpathways, like the body does with aged blood cells at a much higher rateday by day. Much larger amounts of blood are left in veins treated bysclerotherapy or thermo-occlusive methods for metabolism andtransformation. The foam according to the present invention, compared tosclerofoams of prior kind, contains up to 50% less gas which isfavourable as gas amounts are suspected to be responsible for sideeffects of foam therapy like impaired vision or bronchospasms.

Sometimes, it may be useful to remove parts of the whole blood orconcentrate others, e.g. erythrocytes may be reduced to reduce the colorintensity, and fatty remnants may be advisable to remove from thedenaturized blood in patients with elevated blood lipids. Leukocytes maybe removed when fearing pyrogenetic mediator discharge, and vitalthrombocytes may be concentrated to increase the coagulation processwithin the target vessel. For this reason, besides the whole bloodaddressed in the descriptions of the invention, the option to insteaduse fractions of blood is always included. Those skilled in the art knowthe required procedures of cell elimination or concentration byfiltration, hydro-extraction and others.

In particular, for use in sclerotherapy it may be desirable that thesclerosant drug foam according to the present invention comprises activeplatelets, i.e. adhesive platelets that can activate local clotting.Thus, it would be necessary to inactivate the inhibitory proteins andenzymes while maintaining a sufficient amount of active platelets. Thedegree of denaturing can be selected by those skilled in the art. In apreferred embodiment essentially all proteins and enzymes inhibiting thesclerosant drug are inactivated in the partially denatured blood. Theskilled artisan knows methods to determine the degree of denaturing ofthe blood. For example the activity of different enzymes within thepartially denatured blood may be compared to the activity of therespective enzymes in non-denatured blood. Such “indicator” enzymes arewell known in the art. One indicator enzyme is catalase. Thus, thedegree of denaturing of the blood can be tested by the catalase test.The presence of catalase enzyme in the test isolate is detected usinghydrogen peroxide. If blood or partially denatured blood possesscatalase (i.e., is catalase-positive), bubbles of oxygen are observedwhen blood or partially denatured blood is added to hydrogen peroxide.The test is done by placing a drop of hydrogen peroxide on a microscopeslide. An applicator stick is contacted with blood or partiallydenatured and then applied into the hydrogen peroxide drop. In oneembodiment no bubbles of oxygen are observed when partially denaturedblood is applied into a hydrogen peroxide drop.

The sclerosant drug foam according to the invention is for use as amedicament, in particular as a medicament in sclerotherapy.

The method to produce a sclerosant drug foam according to the inventioncomprises the steps of providing denatured blood or denature bloodfractions, dispersing the denatured blood at a temperature of 10-85° C.with a pharmaceutically acceptable liquid wherein preferably thepharmaceutically acceptable liquid is or comprises said at least onesclerosant drug, or mixing the dispersion with said at least onesclerosant drug, finally foaming the dispersion with medical a gassuitable for intravenous use, like O₂, CO₂ or mixtures thereof (FIG. 5a-c). The use of higher temperatures than 85° C. is possible but mayinterfere with the evaporation temperature of alcohols or othersclerosant media unless system pressure is increased. Also lowertemperatures than 10° C. may be used for added fluids, if the purpose israpid cooling. The produced sclerofoam should be at a temperature of10-85° C., preferably 15-40° C., even more preferably 20-37° C. Foamtemperatures of above 37° C. may contribute to an increased denaturingeffect on the endothelium but bear the risk of unwanted thermal damage,e.g. in structures near to the skin.

The basic device to produce sclerosant drug foam according to theinvention (FIG. 5a ) comprises a catheter for blood sampling and foamdistribution (1), a first container (4) for blood collection anddenaturation, an external element for denaturation by heat, radiation orchemicals (6) to be physically or thermically connected to the firstcontainer, a second container (10) for at least one fluid and/or atleast one sclerosant agent, a unit (7 a) to apply mechanical force tothe contents of the first and/or second container for mixing/dispersing,optionally a chopping element (7 b), optionally a filter element (13), athird container to hold the dispersion (14), a fourth containercontaining a medical gas (18), a unit (16) to apply mechanical force tothe contents of the third and/or fourth container for foaming, two-wayswitches, one-way valves, single stop cocks or combinations thereof (2,3, 9, 15, 17) to selectively connect the containers and units, auxiliaryaccess to the device, e.g. to apply negative or positive pressure, or tosupply fluids or gases for foam production or for rinsing (4 a, 8, 11 a,11 b, 19), and connection elements connecting all modular parts.

In the procedure, an amount of blood is taken from the target veinthrough the catheter (1) and guided to the first container (4) where theblood is denatured by help of the denaturation unit (6). The denaturedblood is mixed with a fluid and/or a sclerosant agent from a secondcontainer (10) to form a dispersion by application of mechanical forces(7). If the mixing procedure alone would leave particles above 120 μm, achopping unit (7 b) is added and the dispersion passed once or severaltimes. To ensure no particles above 120 μm are present in thedispersion, it may be filtered (13) and guided to a third container(14). Then a connection to a fourth container (18) providing a medicalgas is established and a foam produced by mixing the gas with thedispersion by applying mechanical force (16). The foam is finallyprovided in one of the containers (14, 18) and transferred to thediseased vein via catheter (1).

In another embodiment, the procedure comprises the steps of denaturingblood by introduction of a pharmaceutically acceptable liquid heated to78-100° C. into the blood containing compartment of the device, or byintroduction of steams of such liquids of 80-130° C. wherein the liquidmay be or may contain at least one sclerosant, or by introduction ofheated gas suitable for intravenous use like O₂ and/or CO₂, or bycombination of these means. After cooling to below 77° C. and adding atleast one sclerosant drug, further dispersing of the mixture isperformed until sufficient small particle size is obtained, and furtherfoaming of the dispersion with present or added gas suitable forintravenous use, like O₂ and/or CO₂ until the desired bubble size isobtained. This embodiment produces the required dispersion withoutrequiring high mechanical forces as there is no solid denatured blood tobe dissolved (FIG. 5b ). The indicator of color change applies to thismethod, but the indicator of change in viscosity does not apply as nosolid body is formed during blood denaturation.

In this embodiment, a device for the production of a sclerosant drugfoam minimizing mechanical forces for mixing and disperging is described(FIG. 5b ), comprising a catheter for blood sampling and foamdistribution (1), a first container (4) for blood collection anddenaturation by heated fluid, an element for supply with heated fluid(6), a second container (10) for at least one sclerosant agent, a unit(16) to apply mechanical force to the contents of the first and/orsecond container for foaming after adding medical gas, an access to addsclerosant or a medical gas (8), or to apply negative or positivepressure or for rinsing (11 a, 11 b); two-way switches, three-wayswitches, one-way valves, single stop cocks or combinations thereof (2,3 a, 3 b, 9) and connection elements connecting all modular parts.

For the foam producing procedure, an amount of blood is taken from thetarget vein through the catheter (1) and guided to the first container(4) where the blood is denatured by help of the denaturation unit (5),in this particular embodiment by mixing with a heated fluid, e.g.isotonic saline or aqua destillata of 80-100° C., then adding at leastone sclerosant agent from a second container (10) to form a dispersion,finally adding a medical gas is added via auxiliary port (8) and foamingperformed by mechanical force (16) or pressure variations or for rinsing(11 a, 11 b). The resulting foam is transferred to the diseased vein viacatheter (1).

In another embodiment, a simplified device for the production of asclerosant drug foam (FIG. 5c ) is described, comprising a catheter forblood sampling and foam distribution (1), a first container (4) forblood collection and denaturation (5), elements for denaturation by heator radiation (5) or chemicals (4 a), a second container (10) for atleast one fluid and/or at least one sclerosant agent, a unit (7) toapply mechanical force to the contents of the first and/or secondcontainer for mixing/dispersing and foaming after adding medical gas, anaccess to add a medical gas (16), two-way switches, one-way valves orsingle stop cocks or combinations thereof (2,3), auxiliary access to thedevice, e.g. to apply negative or positive pressure or for rinsing (11a, 11 b) and connection elements connecting all modular parts.

For the production of blood-based sclerosant foam, an amount of blood istaken from the target vein through the catheter (1) and guided to thefirst container (4) where the blood is denatured by help of thedenaturation unit (5). The denatured blood is mixed with a fluid and asclerosant agent from a second container (10) to form a dispersion byapplication of mechanical forces (7). A medical gas is added viaauxiliary port (8) and foaming performed by mechanical force (7). Thefoam is finally collected in one of the containers (4, 10) andtransferred to the diseased vein via catheter (1).

In all embodiments, the components except the catheter to the targetvein may be miniaturized to fit into the catheter or into a catheterextension with an outer diameter of below 30 mm, preferably below 20 mm,even more preferably below 10 mm.

The device construction, in particular concerning the containers, may bemodular or integral. In a preferred embodiment, the units forheating/denaturation (6), dispersing (7) and foaming (16) are modular.

The containers, connectors, switches and elements for filtering,chopping and foaming may be provided as single parts to be assembled bythe user under sterile conditions prior to use, however preferably allparts are provided completely assembled and sterilized as a one-waysystem, except the external unit for physical denaturation. The switchesmay be common one-way, two-way or three-way cocks for manual handling,they may also be electric, magnetic or electromagnetic, or pressureoperated.

The invention further relates to a kit for the production a sclerosantdrug foam comprising a unit for blood denaturing and dispersing,optionally at least one fluid, optionally at least one sclerosant drug,at least one medical gas, and optionally one or several catheters forvenous access and foam deployment.

The present invention also relates to a treatment of venousinsufficiency the method comprising the steps of:

-   (i) establishing an access to one or several target veins,    preferably to the largest target vein, by use of canulas,    microcatheters or preferably by catheters, and taking of at least    one autologous blood sample of 0.5-4 ml;-   (ii) preparing a sclerosant drug foam by mixing at least one    sclerosant medium with a matrix of disperged denatured blood;-   (ii) injecting the sclerosant drug foam into the target veins    preferably using ultrasound monitoring;-   (iii) removal of intravenous foam conducting elements.

Like outlined previously, the use of catheters is preferred, as foamdeployment is more precise and more efficient when large-lumen device isused for injection because for physical reasons blood replacement inveins by foam is more effective.

The venous access is established by puncture under local anaesthesia. Inshort or very tortuous diseased vein segments usual peripheral venousaccess systems of 0.8-2.2 mm diameter and 40-60 mm in length may be usedfor antegrade or retrograde foam injection. They consist of a cannulacovered by a plastic tube except for the tip and allow direct veinaccess, where the cannula is withdrawn and the tube remains within thevein for a time according to its purpose. However, similar microcatheterproducts with included cannula of 80-200 mm in length and the option todeploy the foam during withdrawal of the catheter are preferred. Forvery large and long diseased veins like saphenous veins (e.g. venasaphena magna et parva) it is preferred to work with catheters of1.2-2.8 mm in diameter, 40-80 cm in length and provided with non-stickproperties and one or several optional sideholes. These catheters areintroduced in SELDINGER technique using a guide wire, or as stand-aloneprocedure using an implemented cannula.

The sclerosant drug foam, as meant for use in humans, is generallyproduced under sterile conditions. Concepts of producing blood-basedsclerosant foam which operate in a closed system are preferred, limitingthe contact to the environment to the supply of liquids, sclerosant andmedical gases under sterile conditions. This also excludes the risk ofblood contamination or sample confusion. Preferably the device isprovided sterile, or can be sterilized.

In one embodiment the sclerosant drug foam is prepared in a devicewithin or a device connected to a catheter. Ideally, the sclerosant drugfoam is dispersed in the pharmaceutically acceptable liquid usingmechanical force, e.g. using a chopping element.

The invention also relates to a method for the production of asclerosant drug foam comprising the steps of:

-   -   (a) denaturing blood by introduction of a pharmaceutically        acceptable liquid heated to 78-100° C. into the blood containing        compartment of A device, or by the introduction of steam of        between 80 and 130° C. wherein the liquid may be or may contain        at least one sclerosant, or by introduction of heated gas        suitable for intravenous use like O₂ and/or CO₂, or by        combination of these means;    -   (b) cooling to below 77° C. and add at least one sclerosant drug        if not included in step (a);    -   (c) further dispersing of the mixture generated in steps (a)-(b)        until the maximum particle size as defined above is reached,    -   (e) further foaming of the dispersion with present or added gas        suitable for intravenous use, like O₂ and/or CO₂, if mean bubble        size is above 120 μm.

The invention relates to various device types.

In one embodiment the device for the production of a sclerosant drugfoam minimizing mechanical forces for mixing and dispersing, comprises:

-   -   (a) 0 a catheter for blood sampling and foam distribution (1),    -   (b) a first container (4) for blood collection and denaturation,    -   (c) an element for supplying the heated fluid (6),    -   (d) a second container (10) for at least one sclerosant agent,    -   (e) a unit (16) for applying mechanical force to the contents of        the first and/or second container for foaming after adding        medical gas,    -   (f) optionally access to add sclerosant or a medical gas (8), or        to apply negative or positive pressure, or for rinsing (11 a, 11        b).    -   (j) optionally two-way switches, three-way switches, one-way        valves, single stop cocks or combinations thereof (2, 3 a, 3 b,        9)    -   (k) connection elements connecting all modular parts,

Here, an amount of blood is taken from the target vein through thecatheter (1) and guided to the first container (4) where the blood isdenatured by help of the denaturation unit (5), in this particularembodiment by mixing with a heated fluid, e.g. isotonic saline ordistilled water of 80° C. to 100° C., then adding at least onesclerosant agent from a second container (10) to form a dispersion,finally adding a medical gas is added via auxiliary port (8) and foamingperformed by mechanical force (16) or pressure variations (8, 11, 4 a).The resulting foam is transferred to the diseased vein via catheter (1).

The invention also relates to a device for the production of asclerosant drug foam comprising:

-   -   (a) a catheter for blood sampling and foam distribution (1),    -   (b) first container (4) for blood collection and denaturation        (5),    -   (c) one or more elements for denaturation by heat or radiation        (5) or chemicals (4 a),    -   (d) a second container (10) for at least one fluid and/or at        least one sclerosant agent,    -   (e) a unit (7) to apply mechanical force to the contents of the        first and/or second container for mixing/dispersing and foaming        after adding medical gas,    -   (f) means for adding a medical gas (16),    -   (j) optionally two-way switches, one-way valves or single stop        cocks or combinations thereof (2,3)    -   (k) optionally auxiliary means for applying negative or positive        pressure, or for rinsing (11 a, 11 b)    -   (l) connection elements connecting all modular parts,

Here, an amount of blood is taken from the target vein through thecatheter (1) and guided to the first container (4) where the blood isdenatured by help of the denaturation unit (5). The denatured blood ismixed with a fluid and a sclerosant agent from a second container (10)to form a dispersion by application of mechanical forces (7). A medicalgas is added via auxiliary port (16) and foaming performed by mechanicalforce (7). The foam is finally collected in one of the containers (4,10) and transferred to the diseased vein via catheter (1).

Preferably, some or all components are miniaturized to fit into thecatheter or into a catheter extension with an outer diameter of below 30mm, preferably below 20 mm, even more preferably below 10 mm.

Preferably, the device is modular.

Preferably, the device is integral, including or excluding theheating/denaturation unit (6).

Preferably the one or more of the containers are a syringe.

The invention relates also to a method of treating venous insufficiencyusing a sclerosant drug foam comprising the steps of

-   -   (i) establishing an access to one or several target veins,        preferably to the largest target vein, by use of canulas,        microcatheters or preferably catheters, and taking of at least        one autologous blood sample;    -   (ii) preparing a sclerosant drug foam as defined above;    -   (ii) injecting the sclerosant drug foam into the target veins        preferably using ultrasound monitoring;    -   (iii) removing the intravenous foam conducting elements        (catheter).

EXAMPLES

Comparison of Regular Sclerosant Foam with Denatured Blood Based Foam

5 different kinds of foams were evaluated concerning velocity of foamcollapse:

1.) (HS 78/7) innovative foam prepared from 2 ml human whole bloodheated in a 10 ml plastic syringe to 78 degrees Celsius for 7 minutes,resting in room temperature for 5 minutes, then mixed with 4 mlAethoxysklerol 1% (Kreussler Pharma Germany) to obtain a dispersion,passed through a 200 micron filter and then foamed with room airaccording to the Tessari method (10× movement to and from between twoidentical syringes).

2.) (HS 78/30) same procedure as 1.) but blood sample heated for 30minutes

3.) (blood+AE) same components as 1.) but using native human whole bloodwithout exposure to heat >21 degrees Celsius (room temperature)

4.) (AE 2+8) standard sclerofoam like used by today's physiciansprepared from 2 ml Aethoxysklerol 2% and 8 ml room air according toTessari method.

5.) (AE2, 6+4) alternative sclerofoam containing the same volume offluids as example 1.), but without denatured blood.

The velocity of foam collapse was measured according to the volume offluid accumulating at the bottom of the sample syringes stored in anupright position. During decay of foam bubbles these will grow andapparently the level of foam may remain the same, but accumulating fluidis a valid indicator of foam collapse. Half-life was defined as the timepassed unto half of the initial fluid volume was showing at the bottomof the syringe. Measurements were performed after minute 1, 2, 3, 4, 5,30, 60 and 24 hours (see FIGS. 7 a-d), Tables 2 and 3.

TABLE 2 Overview of tested sclerosant foams foam 1 2 3 4 5 HS- HS-blood + AE AE2, 78/7 78/30 AE 2 + 8 6 + 4 heated to . . . degree 78/778/30 not not not C. for . . . minutes heated heated heated blood (ml) 22 2 0 0 sclerosant (ml) 4 4 4 2 6 concentration AE 1 1 1 2 0.666 volumeAE ml 0.04 0.04 0.04 0.04 0.03996 total volume of fluid (ml) 6 6 6 2 6total volume of gas (ml) 4 4 4 8 4

TABLE 3 time dependent collapse of sclerosant foams (see also FIG. 7)foam 1 2 3 4 5 foam collapse time/min. ml ml ml ml ml fluid in mlindicating 1 0.00 nd 4.00 0.00 1.00 collapse of foam 2 0.00 nd 5.80 1.004.00 3 0.00 nd 6.00 1.50 5.00 4 0.00 nd 6.00 2.00 5.25 5 0.00 nd 6.002.00 5.50 15 0.50 nd 6.00 2.00 6.00 30 0.80 nd 6.00 2.00 6.00 60 1.00 nd6.00 2.00 6.00 24 h 1.20 nd 6.00 2.00 6.00 nd = not determinable

Results: Sample 1 showed a very slow foam disintegration collecting just1.2 ml of fluid after 24 h. Thus, the volume half-life is >24 h. Sample2 showed a rapid disintegration of a brighter, air-containing fractionof about 50% of volume, and a darker, depositing section containingparticles. The foam disintegration was assessed as “not determinable” asno fluid collection was distinguishable from the deposit. Due to therapid formation of a large unfoamed deposit, such foam would beunacceptable for medical use. Sample 3 showed the fastest disintegrationof all foam samples with 66.6% of the used fluid volume being visiblealready after one minute. The half-live is <1 minute. The comparison tosample 1 proves that the increased half-life of the innovative foam isnot due to the ingredients which are chemically identical(blood-sclerosant-air), but to the use of denaturized blood. Sample 4showed disintegration of half of foamed volume at about 2 minutes (seetable 2). This correlates with numerous literature date of foamhalf-lifes of 30-180 seconds. The comparison to sample 1 proves thelarge increase of half-life obtained by the invention. Sample 4 containsas much sclerosant fluid as sample 1, and the same amount of sclerosantsubstance. However, the decay is faster than for standard microfoam(sample 4). This result proves that the amount of fluid is not the causefor the increased half-life of the innovative foam.

Furthermore the sclerosant drug foam according to the invention (1 inthe above example) shows also a greater half live in veins, as can beseen in ultrasound images (FIG. 8) compared to regular sclerosant foam(4 in the above example).

Further properties of the sclerosant drug foam according to the presentinvention are shown in the following tables:

TABLE 4 Closure of great saphenous veins 30 minutes after sclerotherapyusing 1% aethoxysklerol (AE) in 20 patients, in color duplex ultrasoundexaminations in the standing individual. common foam (2 ml AE, 8 ml roomair) 1/10 10% foam according to the intervention 9/10 90% (1.5 mlmatrix, 2 ml AE, 6.5 ml room air)Comparison of Foam Viscosity

Plastic syringes of 10 ml volume were filled with sclerosant foams a)standard, prepared with 2 ml Aethoxysklerol 1% plus 8 ml gas (30%CO₂+70% O₂) and b) a foam according to the invention prepared from 2 mlAethoxysklerol 1%, 2 ml fresh human whole blood, 1 ml Aqua dest., and 5ml gas (30% CO₂+70% O₂) by use of TESSARI method. The syringes wereclosed at the tip, opened at the other side and fixed in an inclinedposition of 60 degrees from horizontal. A plastic ball of 13 mm indiameter and a weight of 1.6 grams was positioned at the foam surfaceand released. The time of passage through the foam was recorded. Themeasurements were repeated five times. This setting was chosen ascommercial device for measurements of viscosities is available forfluids, but not for foam.

Results: Within the standard foam, the ball moved with a mean of 1.9cm/s while in the foam prepared with a blood-derived matrix the balljust reached a mean of 0.2 cm/s. This indicates that the viscosity ofthe inventive foam is much higher than in standard sclerofoams. Theviscosity will depend not only on the ingredients, but also onmechanical forces when mixing.

Blood-Derived Matrix without Red Blood Cells

Common sclerofoam (2 ml Aethoxysklerol 1%+8 ml gas mixture 30% CO₂, 70%O₂) was compared to a foam according to the invention, prepared bytaking a whole blood sample of 5 ml, extracting red blood cells bycentrifugation at 1000 UPM for 10 minutes end then exposing a 2 mlsample to temperature of 95° C. for 5 minutes, finally foaming it with 2ml Aethoxysklerol 1%+6 ml gas mixture 30% CO₂, 70% O₂. Both samples werefoamed simultaneously according to TESSARI method and then thedisintegration of the foams was observed for 30 minutes. Results: Thehalf-live, measured according to accumulating fluid at the bottom of thesample vessels, was 2.5 minutes for standard and 27.5 minutes for theinventive foam. Thus, the obtained increase of half-live is less thanachieved with a foam prepared on whole blood basis, but stillsignificantly superior to common sclerofoam. A foam with reducedcontents of red blood cells may be used in superficial veins to avoiddiscolorations. As in foams of this kind no red blood cells are presentto indicate appropriate denaturation, all parameters (temperature, time,sample geometry) were chosen identical to the experience of whole-bloodcontaining samples.

FIGURE CAPTIONS

FIG. 1, a-b: ultrasound scan of a varicose vein after injection ofpolidocanol microfoam, a: longitudinal view, b: cross-sectional view.The contents of sound reflecting gas is responsible for the visibilityof the foam column, but also for the formation of acoustic shadows(arrows) which hide valuable information.

FIG. 2 a-b: Ultrasound images after application of a foam according tothe invention, a) longitudinal and b) cross-sectional. The foam depositis clearly visible (arrows), but transparent to ultrasound to a largeextent.

FIG. 3 a-c: Comparison of common white sclerofoams (M2, GM7-04) preparedwith 2 ml Aethoxysklerol 2% plus 8 ml room air according to TessariMethod (M2) resp. 2 ml Aethoxysklerol 2%, 2 ml glucose 70% plus 6 mlroom air according to Tessari Method 2% (GM7-04), to a sclerofoamaccording to the invention (HS2) prepared with 2 ml denatured bloodmatrix, 2 ml Aethoxysklerol 2% and 6 ml room air. Due to the contents ofdenatured whole blood, the color of this sample is brownish. The clockshows the time after mixing. In the common sclerofoam, disintegration iseven visible at the bottom of the vessels after 30 seconds (a) and hasreached 15-20% after 90 seconds (b), corresponding to an assumedhalf-life of up to 210 seconds. In this sample the improved foam isstill stable after 4 hours with partially enlarged bubbles butdisintegrated fluid parts of less than 15% (c).

FIG. 4 a-d: Due to its higher stiffness or viscosity, the foam can bedistributed within veins very precisely. This is demonstrated in vitrousing transparent tubes showing common foam (Aethoxysklerol 1%, 2 ml,plus 8 ml filtrated room air, 100 s post mixing) in a) vertical and b)inclined tube position, compared to foam according to the invention(Aethoxysklerol 1%, 2 ml, 2 ml denatured blood matrix, plus 6 mlfiltrated room air, at 100 s post mixing), c) vertical and d) evenhorizontal tube position. Common foam distributes diffuse andwedge-shaped (b), the curves in the foam border are due to inhomogenousnon-stick coating of the test tubes. The invented foam forms a distinctrectangular border line at any spatial orientation of the test tubes(c,d).

FIG. 5a : Scheme of a device to prepare injectable sclerofoam using amatrix based on autologous blood, using a catheter (1) with input-outputswitch (IOS, 2) wherein IOS may either be two-way stopcocks or pairs ofsingle stopcocks, connected to first container (4) which is adapted toan integral or exchangeable heat providing and/or heat transferring unit(6). The suitable degree of blood denaturation is determined by adetector system (4 b) attached to the heat-denaturing unit (5) which isconnected via optional IOS (3, 9) to a second container (10) whileintegrating a disperging means (7 a), optionally with a cutting device(7 b). Optional connectors for external supply of fluid or sclerosant(8), for rinsing or to apply positive or negative pressure (11 a, 11 b,19 a, 19 b) may be added in suitable locations related to containers 4or 10. The dotted lines may represent a single passage from (4) to (10),or multiple to- and from passages. The containers (4) and (10) andrelated IOS and connectors may be summarized as denaturing anddisperging unit (12).

The dispersion is optionally passed through a filter element (13) to thefoaming unit (20), consisting of a container to hold the dispersion(14), a container to contain a medical gas (18) and a means to applymechanical force or energy (16). Furthermore, IOS (15, 17) and a meansto externally supply a medical gas (19).

The lines connecting the containers indicate flow of blood (fat line),dispersion (fat dotted line), and foam (small dotted line).

FIG. 5b : Blood denaturation may also be performed by use of heatedfluid or steam. In this case, a heating element (6) is attached to oneof the containers to provide heated fluid, heated sclerosant and/orsteam resp. heated gas, and the heated substance is guided to thedenaturation container (4).

FIG. 5c : For simplification, the foaming unit (20) may be replaced bythe containers and other elements of unit (12), not using a filterelement (13) or providing it as an option in a switched bypass arrayconnecting containers (4) and (10), and using auxilliary access points(8, 11) to supply a medical gas.

FIG. 6: Heat—denatured blood forming an inherent solid body, in thisexample comparing samples prepared in a syringe at proceduraltemperatures of 80 and 95° C. and spread on a tissue.

FIG. 7: Comparison of the stability of a sclerosant drug foam accordingto the invention at different time points after generation 7 a) 1 min, 7b) 3 min, 7 c) 30 min, 7 d) 24 h

FIG. 8: Ultrasound comparison of regular sclerosant foam and foamaccording to the present invention. A common sclerosant foam preparedwith 2 ml Aethoxysklerol 1% and 8 ml room air according to Tessarimethod was injected to fill a branched human vein of 5 mm in diameter(m), and a sample of the inventive foam prepared from 1 ml denaturedwhole blood was injected to fill a parallel segment of the same veinwith 5 mm diameter (hs). After 4 hours, ultrasound showed no residualcommon foam (m), while the inventive foam is still present (hs).

FIG. 9: Ball test measurement of viscosity of common sclerosant foam (9a) and new sclerosant foam according to the present invention (9 b).

The invention claimed is:
 1. An injectable sclerosant drug foamcomprising: (i) a matrix; (ii) at least one fluid; (iii) at least onesclerosant drug; and (iv) a medical gas or medical gas mixtureacceptable for intravenous use, wherein said matrix has physicalproperties comparable to denatured blood, wherein the denatured bloodwas denatured as follows: a fresh human venous whole blood sample of 1ml volume is heated in a cylindrical polyethylene container with aninner diameter of 3 mm and an outer diameter of 3.4 mm for about 0.5min. to about 10 min. at a temperature of about between 70° C. and 100°C.
 2. The sclerosant drug foam of claim 1, wherein the matrix comprisesdenatured blood.
 3. The sclerosant drug foam of claim 2, wherein thedenatured blood is dispersed in a pharmaceutically acceptable liquid andoptionally wherein the pharmaceutically acceptable liquid is thesclerosant drug or the sclerosant drug is dissolved or dispersed in thepharmaceutically acceptable liquid.
 4. The sclerosant drug foam of claim1, wherein the denatured blood is autologous blood of the respectivepatient.
 5. The sclerosant drug foam of claim 1, wherein blood has beendenatured by chemical means, heat, or radiation, wherein said radiationis an electromagnetic radiation.
 6. The sclerosant drug foam of claim 1,wherein at least one sclerosant drug is selected from the groupconsisting of sodium tetradecyl sulfate, ethanol, or polidocanol.
 7. Thesclerosant drug foam of claim 1, wherein the dispersed partiallydenatured blood has a maximum solid particle size of 5-300 μm.
 8. Thesclerosant drug foam of claim 1, wherein the foam has a bubble size of10-300 μm.
 9. A method for producing the sclerosant drug foam of claim 1comprising the steps of: (a) providing a matrix, wherein said matrix hasphysical properties comparable to denatured blood, wherein the denaturedblood was denatured as follows: a fresh human venous whole blood sampleof 1 ml volume is heated in a cylindrical polyethylene container with aninner diameter of 3 mm and an outer diameter of 3.4 mm for about 0.5min. to about 10 min. at a temperature of about between 70° C. and 100°C.; (b) providing at least one pharmaceutically acceptable liquid and atleast one sclerosant drug; (c) dispersing the matrix at a temperature ofbetween 10° C. and 77° C. in the pharmaceutically acceptable liquid,wherein the pharmaceutically acceptable liquid comprises said at leastone sclerosant drug; and (d) foaming the dispersion with medical a gassuitable for intravenous use wherein the medical gas is selected formO₂, CO₂ or mixtures thereof.
 10. A method of treating venousinsufficiency using a sclerosant drug foam comprising the steps of (i)establishing an access to one or several target veins by use of canulas,microcatheters or catheters, and optionally taking of at least oneautologous blood sample; (ii) preparing a sclerosant drug foam of claim1; (iii) injecting the sclerosant drug foam into the target veinspreferably using ultrasound monitoring; and (iv) removing the canulas,microcatheters, or catheters previously used to establish an access tothe target veins.